The activists who demanded Zimmerman be arrested got their wish, but that wish suddenly evolved from a demand that the Floridian face charges to the demand that he be convicted. Without waiting for the input of a grand jury, Corey obliged those who wanted to see Zimmerman in handcuffs. The rest of the story is history. The charges were too excessive, the burden of proof too steep. Zimmerman was acquitted and Corey was disgraced.

This familiar story might be playing out again, in Baltimore this time. The city’s prosecutor, Marilyn Mosby, found herself thrust into the limelight when she announced her intention to pursue criminal charges against the six officers involved in the arrest of Freddie Gray, a young Baltimore man who died in police custody under suspicious circumstances and whose death sparked a series of violent riots.

To prove that police used undue force when subduing or restraining a criminal suspect is a high hurdle to overcome. In an op-ed for USA Today, former federal prosecutor Gregory Wallance indicated that prosecutors might have reached too far, yet again.

Already, issues are emerging in the Gray case that give cause for concern. Crucial to the prosecution’s case is the claim that the police had no probable cause to arrest Gray for possession of a knife with an automatic spring for opening and closing, i.e., a switchblade, as alleged in the arrest report. In fact, Mosby asserted publicly in her news conference announcing the charges that “the knife was not a switchblade.” This is a crucial issue because the prosecution’s case is much stronger if the officers had no grounds to arrest Gray in the first place. Otherwise, the defense can argue that they were only doing their job when Gray was put in the police van under restraints.

Indeed, the very first defense motion, filed Monday, claimed that the knife was illegal and sought permission to examine it. According to news reports, before the charges were brought, a Baltimore police task force report (not yet made public) found that the knife was “spring-assisted” and illegal under local law.

This doesn’t mean Mosby got it wrong or shouldn’t have brought the charges, but it does illustrate why, especially in police brutality cases, prosecutors must be thorough. Did she or her investigators interview the authors of the report to better understand why they reached that conclusion, or whether it was animated by bias in favor of the officers? Did Mosby ask an independent expert to examine the knife and give her an objective assessment? Did she even look at the knife? We don’t know but Mosby waited only about 24 hours after receiving the task force report before filing the charges.

CNN reported on Thursday that sources linked to Baltimore police revealed information to the network that undercut the charges brought against officers by Mosby.

The CNN reporters and anchors noted, and not without reason, that the leaks they have heard that support the defendants’ claims are likely designed to create doubt about the guilt of these six officers. Nevertheless, the suggestion that an autopsy does not support the charge of homicide and that Gray’s arrest was justified are not minor claims.

It is possible that there was prosecutable police misconduct in the arrest and ultimate death of Freddie Gray. It’s just as possible that the charges against these officers are unsupported and that prosecutors were compelled to file them in order to sate a restless mob. If the latter ends up being the case, don’t expect anyone to learn any hard lessons from this episode. Be prepared for history to repeat yet again, and sooner than you might hope.